Grinding mill



Nov. 3, 1936. R. D. M cDONALD GRINDING MILL Filed April 13, 1934Patented Nov. 3, 1936 UNITED STATES PATENT OFFICE GR INDING MILLApplication April 13, 1934, Serial No. 720,348

9 2 Claims.

The invention relates to feed grinding mills, and particularly to thoseof the so-called hammer type having a comminuting rotor in a casingprovided with a feed opening and a hopper to lead the material to bereduced thereto. In operating these mills, the high speed of the rotorfrequently causes chunks of the material in process, such as cobs orbroken parts thereof, to be thrown out of the drum and feed opening withgreat velocity. When the hopper is not full, such thrown out partsconstitute a serious safety hazard endangering life and limb of the millattendant.

More particularly, therefore, the invention relates to means forovercoming such hazard.

The object of the invention is to provide an improved baiiie or gateconstruction to be located in the feed throat of the mill to preventparts of the material in process from being thrown out of the machine.

A further object of the invention is to provide such baille or gatewhich will not interfere with or constitute any obstruction to thefeeding operation.

Another object is to provide such device which will be fool proof andsimple and which can be applied to standard mills without altering theconstruction thereof.

Further important objects will become apparent to those familiar withthis art as the disclosure is more fully made.

These objects are achieved by mounting a shaft across the throat of thefeed hopper and pivotally hanging therefrom a plurality of spaced bafliearms which substantially obstruct the throat passage and cannot swingoutwardly, but only inwardly relative to the feed opening of the mill.Thus, when a cob or part thereof is thrown outwardly, it will hit one ormore of these baflle arms and be stopped in its flight, the cob or partthen having to feed back into the reducing chamber.

In the drawing showing a practicable form of the invention,-

Figure 1 is a central, vertical cross-sectional view through a hammermill, showing the baffle or gate of this invention associated therewith;

and.

Figure 2 is a cross-sectional view through the hopper of the mill asseen along the line 2--2 of Figure 1 to show a face view of the baflie.

The mill shown is of a well known type having a base l0, upon which ismounted a vertically disposed cylindrical drum ii to form .a reducingchamber in which is the comminuting rotor i2 carried on a shaft i8mounted in a wall of the drum by means of bracket l4, said shaft beingdriven from a belt pulley IS. The rotor I2 carries peripherally disposedswinging hammers i6 and on its face adjacent the feed opening il, apreliminary cutting and breaking knife element 5 l8. The feed openinghas the throat IQ of a hopper 20 associated therewith, said hopper beingcarried on the adjacent wall of the drum H, as shown. The hopper issupported by a brace 2 I. The inner periphery of the drum carries ascreen 10 22 which cooperates with the hammers l6 to help reduce thematerial in process. The wall ll adjacent the knife l8 carries astationary shear bar 23 which cooperates with the knife i8 to cut upears of corn, as shown in Figure 1. 15

In practice it frequently happens when the hopper is about empty thatthe rotor hammers 16 operating at high speed bat a cob, or broken partthereof, out of the feed opening I! and the hopper 20. Obviously thisinvolves a serious hazard to the safety of the attendant. Thecooperating action of the knife l8 and shear bar 23 acts frequently alsoto push the infeeding ears of corn back toward the hopper. To preventthis danger, a baffle or gate is provided which will now be described.Such gate also serves to hold the ears against being pushed back intothe hopper under the force of the knife.

Adjacent the top of the throat iii, the hopper 20 carries a cross shaft24 from which is pendently and pivotally hung a series of spaced bafflearms 25, which substantially obstruct the entrance to the throat i9.These arms 26 can swing inwardly under the press of feed toward therotor, but they cannot swing backwardly toward the hopper from the fullline position shown in Figure 1, because the lower ends of the armscontact the upward slope of the bottom of the hopper. These pivoted arms25 easily swing inwardly and form no impediment to the infeed ofmaterial, which moves down the hopper by gravity over the lower slopedsurface thereof. Also these arms work and function independently of eachother as occasion requires. The arms or fingers 25 are spaced from theplane of movement of the knife 5 Iii a distance approximately theaverage length of an ear of corn. Consequently these arms are in properposition to hold the ears against being pushed back into the hopper whenthe knife I8 is cutting them. Also, it is impossible for pieces 50 ofthe cobs to be thrown out of the hopper.

The use and operation of the baiile gate mechanism, of course, is clearfrom the above description and need not be further amplified. It can beseen that the desired objects heretofore recited are attained.

It is the intention to cover all changes and modiflcations which do notdepart from the spirit and its low end adjacent the feed opening. ashear bar in said throat cooperating with the knife to cut cobs, of abaflle mechanism in the hopper substantially occupying the entrance tothe throat, said mechanism comprising a series of spaced independentlyswingable arms, said baflle mechanism being spaced from the shear bar adistance approximating the average length of a cob, the lower ends ofsaid arms normally contacting the sloping bottom whereby under the pressof infed material the arms may swing inwardly toward the chamber and thesloping bottom serving as a stop to limit movement of the arms in anopposite direction beyond their normal bottom contacting positions.

2. The combination with an upright mill having a reducing chamberenclosing a rotor operating on a horizontal axis, a feed hopper having adownwardly sloping bottom and terminating in a throat portion adjacentthe low end of the bottom for feeding material by gravity through a feedopening formed in a side wall of the chamber, said hopper being disposedat substantially a right angle to the face of said wall whereby thematerial is fed to the face of the rotor, the bottom of said hopperbeing stationary, of a baille mechanism in the hopper comprising meansfor carrying a plurality of independently movable, spaced, pivoted andpendently hung arms which normally substantially close the throatportion, said arms being free to swing inwardly toward the chamber feedopening under the press of feed of material moving down said bottom, the

said stationary sloped bottom serving as a stop to limit swingingmovement of the arms in a direction away from said chamber, said latterlimiting action occurring when the lower ends of the arms strike saidbottom.

RAYMORE D. MACDONALD.

